Bally MPU Corosion – Woes and Repair continues

MPU Pre-Cleaning

MPU prior to cleaning process

Well tonight – I finally got in the mental space to re-approach working on the MPU for the Dolly Parton pinball machine.  I was disheartened when I finished the installation of the U8 last week.

I had verified all the connections were correct – and replaced the capacitor just below the IC.  Everything then tested as I expected, so with great hope I put the board in the pin.  My hopes were dashed when I powered the game on. Nothing happened other than a bit of beeoooop noise once. I flipped the power a couple of times – not expecting anything different, but hoping.

Dejected I took the board out, and placed it on my card table work bench.

So, a week later (today) I got the gumption up to work on the board again.  I figured the reset section was not working correctly.  The green LED comes on, but doesn’t go through the flicker/flash boot sequence.  So somewhere something in that section must be out of whack.  This is not coincidentally the same section that is usually directly affected by corrosion.

Today – I cut out and de-soldered everything else in this area. Imagine my surprise when I went to remove one of the larger resistors in this section the lead popped right off.  Apparently there was more corrosion problems than I had assumed.

After sanding, scrubbing, cleaning I began to put in all the replacement parts that I had purchased last week for this section.  I spent about three hours on this process I had one spot left for a resistor. I was annoyed after going through my entire box of parts and rechecking the bands on every loose resistor that I have.

I need to purchase one 20k ohm resistor to finish this project. Annoyed as I had gone with a list to the great local supplystore (ACK Electronics), and thought I’d purchased everything needed… but it appears I missed one item.  I did get one resistor that didn’t match anything on my list – so it must be what’s wrong.

Guess I’ll be back to the store this week unless someone has one on hand they want to drop by. 😉

I had been hoping to see if this would bring the machine back to life – but it’ll be a bit longer until we find out.

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One Response to Bally MPU Corosion – Woes and Repair continues

  1. avannoy says:

    I just looked at a Future Spa to buy this week. I took of the back glass and even looked at the boards. At first glance they looked good. I’m standing on the right side of the game (the side the door opens from) and for the longest time I don’t realize this two huge burn stops on the fliptronic board! Plus a resistor with one lead completely burned off and just hanging there.

    So… after saying all of that, what I’m trying to say, it’s just so easy to miss one little solder joint if I can miss that hell of a mess!

    -Aaron of

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